Improving Communication Efficiency

ABSTRACT

There is provided a method including detecting, by an apparatus, a first wireless access option; determining whether or not the first wireless access option shares at least part of a backbone with a second wireless access option; and deciding whether or not to associate with the first wireless access option at least partly on the basis of the determination.

FIELD

The invention relates generally to wireless communication networks. Moreparticularly, the invention relates to improving communicationefficiency in a case where a user terminal may connect to severalwireless access nodes or networks simultaneously.

BACKGROUND

For wireless communications, there are different technologies andnetwork types, comprising different kinds of long range and short rangenetworks. It may also be that a single device may connect to severalaccess nodes at the same time. In this way multiple paths may begenerated for the communication.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the invention, there are provided methods asspecified in claims 1 and 22.

According to an aspect of the invention, there are provided apparatusesas specified in claims 24, 45, and 47.

According to an aspect of the invention, there is provided a computerprogram product as specified in claim 48.

According to an aspect of the invention, there is provided acomputer-readable distribution medium carrying the above-mentionedcomputer program product.

According to an aspect of the invention, there is provided an apparatuscomprising means for performing any of the embodiments as described inthe appended claims.

Embodiments of the invention are defined in the dependent claims.

LIST OF DRAWINGS

In the following, the invention will be described in greater detail withreference to the embodiments and the accompanying drawings, in which

FIG. 1 presents a network, according to an embodiment;

FIGS. 2 to 4, 6 and 7 show methods according to some embodiments;

FIG. 5 shows scenarios for measuring the backbone performance, accordingto some embodiments; and

FIGS. 8 and 9 illustrate apparatuses, according to some embodiments.

DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplary. Although the specification mayrefer to “an”, “one”, or “some” embodiment(s) in several locations ofthe text, this does not necessarily mean that each reference is made tothe same embodiment(s), or that a particular feature only applies to asingle embodiment. Single features of different embodiments may also becombined to provide other embodiments.

The number of IEEE 802.11-enabled mobile devices is ever increasing. TheIEEE 802.11 is a set of standards for implementing wireless local areanetwork (WLAN), also known as the Wi-Fi. Such an IEEE 802.11-enabledstation (STA), such as the user terminals 100 to 102 in FIG. 1, mayassociate with one or more access points (APs) 104, 106, and 108. TheSTA 100 to 102 may comprise a mobile phone, a palm computer, a wristcomputer, a laptop, a personal computer, or any device capable to accessthe wireless radio access network, such as the WLAN. The access points104 to 108 may be WLAN base stations, for example.

Some APs or AP devices 102 to 108 may be capable to physically co-locatemultiple networks, e.g. the same AP may offer multiple networks with thesame hardware. Each network may have own unique service set identifier(SSID), such as “1”, “2”, and “3” for an AP 104 as shown in FIG. 1. EachAP 104 to 108 is typically connected to the Internet 110 with a singlebackbone connection 112. Further, the AP 104 may be located at a singlelocation and the AP 104 may operate on multiple channels. In differentfrequencies the performance of the AP 104 may differ, but not as much asif many AP devices were present to offer the multiple networks. Inaddition to this, there are network topologies, such as in homes or inshop/restaurants, in which multiple AP devices are connected through thesame backbone to the Internet 110. In such case, multiple AP devicesshare the same, common backbone data delivery capacity to the Internet110. For example, in FIG. 1, the APs 104 and 106 are sharing the samelink 112 to the Internet 110, but the APs 104 and 108 are connectedthrough different backbone links 112 and 114, respectively, to theinternet 110.

As shown, the APs 104 to 108 may be connected to the Internet 110 and/orto a local server 116 via routers/switches 120 and 122. In these cases,the throughputs of Internet traffic and local server traffic may differ.Typically, the throughput to the local server is limited by the airinterface performance between the APs 104 to 108 and the STAs 100 to102, whereas the Internet throughput is limited by the backbone link112/114 capacity. For instance, the APs 104 and 106 are connected to thesame local server 116 via the router/switch 120. The data throughput tothe server 116 is not limited by the Internet backbone throughput.

As indicated earlier, the hosts' or STAs' 100 to 102 wireless radios maysupport and maintain concurrent associations to at least two APs 104 to108. The concurrent associations may enable the STAs 100 to 102 toselect among a larger set of transmission paths and help in handovers(HOs). The operation with multiple paths may improve traffic deliveryreliability, e.g. when the air interface links to the APs 104 to 108 areweak. The use of simultaneous associations may also increase thethroughput, e.g. when the backbone links 112/114 are the bottlenecks ofthe transmission capacity. Indeed, there may be cases where thetransmission capacities of the wireless access networks “1”, “2”, “3”,and “4” are higher than the throughput of the backbone network 112/114that connects the wireless networks to the Internet 110. Therefore, itmay be assumed that the bottleneck is in wired lines 112/114 (e.g. suchas in the Asymmetric Digital Subscriber Line (ADSL) modem link). Inorder to increase the throughput, the terminals 100 to 102 may establisha new link/association to another wireless access network “1”, “2”, “3”,and/or “4” or to another wireless access point 104 to 108. However, itmay be that throughput is not increased via this approach. The reasonmay be that the two access networks, such as wireless access networks“1” and “2”, or two APs, such as APS 104 and 106, share the samebottleneck backbone link 112.

In order to optimize the STAs' 100 to 102 operation and efficiency, itis proposed that the STA (e.g. such as the STA 100) utilizes a backbonetopology and throughput information in deciding whether parallelassociations to multiple wireless access options (e.g. to multiple APs104 to 108) increase also the throughput in addition to improving thereliability. As a result, the STA 100 may decide whether to associate toanother AP and/or which operation mode to use in the new association.

As shown in FIG. 2, it is proposed that the STA 100 detects in step 200a first wireless access option. This may happen by detecting the beacontransmitted by an access point of the first wireless access option, forexample. Further, a specific database may download to STA's 100 memorythe identifiers of the APs 104 to 108 to which the terminal 100 isallowed to associate. For instance, the Access Network Detection andSelection Function (ANDSF) define a set of parameters that may restrictthe access to some APs/networks. The identifiers may be used as toselect the AP 104 to 108 for association. The server specific databasesystem may also provide information of the APs 104 to 108 that areavailable at specific locations. This information may also include mainoperating parameters, such as versions of the radio system, itscapabilities, information regarding the applied backbone, etc.

Thereafter, in step 202, the STA 100 further determines whether or notthe first wireless access option shares at least part of a backbone witha second wireless access option. In an embodiment, the shared (common)at least part of the backbone comprises a bottleneck 112/114 to theInternet 110. The determination in step 202 may be done in a pluralityof manners, as will be described later.

In an embodiment, the first and second wireless access optionscorrespond to a same wireless access network, such as the network withthe SSID=“1”, provided by two different access points, such as APs 104and 106. Although not shown in FIG. 1, these APs providing the samewireless access network may have different internet backbones. Forinstance, one of the APs is connected to first ADSL, while the other ofthe two APs is connected to a second ADSL. A basic service setidentifier (BSSID) may identify the AP for the STA 100. The BSSID may bethe medium access control (MAC) address of the respective AP.

In another embodiment, the first and second wireless access optionscorrespond to different wireless access networks, such as the networkswith SSIDs=“1” and “2” provided by a same AP, such as the AP 104, or bydifferent APs. An example of the latter case in which different wirelessaccess networks are provided by different APs may be, as shown in FIG.1, a case where the AP 104 offers the network with SSID=“1” and the AP108 offers the network with SSID=“4”. In an embodiment, even thoughbeing provided by the same AP, the backbone paths to the Internet 110may be different, depending on the network configurations. For example,one wireless access network may have access to more sites and usedifferent routers, etc. In an embodiment, the wireless access networksshare the at least part of the same bottleneck backbone link 112/114.

In an embodiment, the wireless access network may be the WLAN. In anembodiment, the wireless access network may be a cellular network, suchas the Long Term Evolution (LTE) or the LTE-Advanced (LTE-A) of the3^(rd) Generation Partnership Project (3GPP). In general, the concept ofthe wireless access network is to be considered broadly. It should benoted that some STAs may implement both the cellular LTE/LTE-A radio andthe WLAN radio. Further, both of the cellular and WLAN networks may beconnected with the same or different backbone link 112/114 to theInternet 110.

In an embodiment, the first and second wireless access options maycorrespond to different radio access technologies (RATs). For example,the first wireless access option may use WLAN, whereas the secondwireless access option applies a cellular RAT, such as one of thefollowing: Worldwide Interoperability for Microwave Access (WiMAX),Global System for Mobile communications (GSM, 2G), GSM EDGE radio accessNetwork (GERAN), General Packet Radio Service (GRPS), Universal MobileTelecommunication System (UMTS, 3G) based on basic wideband-codedivision multiple access (W-CDMA), high-speed packet access (HSPA), LTE,and/or LTE-A.

Finally, in step 204, the STA 100 decides whether or not to associatewith the first wireless access option at least partly on the basis ofthe determination. If it is determined that the wireless access optionsshare at least part of the same backbone/transport link 112/114 to theInternet, the concurrent association with both of the wireless accessoptions may not improve the total throughput of the STA 100. For the STA100, which is capable to operate concurrently in multiple APs 104 to 108(including multiple WLAN APs, but also APs mixing different accesstechnologies, such as WLAN and cellular 3GPP radios), it may bebeneficial to select a set of APs 104 to 108 that provide the bestperformance. Therefore, a discovery mechanism for detecting the APs 104to 108 to associate with may take into account the backbone link 112/114performance of the APs 104 to 108. The determination of the APs 104 to108 to associate with may thus consider whether the backbones 112 and114 are dependent (e.g. the AP 104 is sharing the same backbone link 112with the AP 106 and possibly with a femtocell, such as Home NodeB orHome eNodeB) or independent (e.g. the AP 108 has individual backboneconnection 114 to the Internet 110).

In an embodiment, the STA 100 may further detect the second wirelessaccess option, possibly via beacon signals corresponding to the secondwireless option.

In an embodiment, the STA 100 is associated to/with the second wirelessaccess option while detecting the first wireless access option. Let usin the following imagine that the STA 100 is currently associated to theSSID “1” provided by the AP 104 (i.e. the AP 104/SSID “1” is the secondwireless access option). The first wireless option may in such case be anetwork provided by the other two APs 106 and 108, or the networks withSSID “2” or “3” provided by the AP 104, for example.

Imagine further that the STA 100 detects the wireless access optionsprovided by the APs 106, which share at least part of the same backbone.As such, the shared, common backbone link 112 may limit the totalthroughput of the STA 100 and the total throughput of the STA 100 maynot be increased by associating to/with both of the APs 104 and 106having the same backbone link 112. On the other hand, if the availablewireless access options do not share the same backbone, as is the casewith the APs 104 and 108, then it may be beneficial to associate to theAP 108 in addition to the AP 104.

Let us now consider how the STA 100 may determine are the two or morewireless access options sharing the backbone/transport link 112/114. Inan embodiment, as shown in FIG. 3, the STA 100 may transmit a requestmessage 302 to a network node 300, wherein the request message 302 isfor receiving a wireless access information message 306 from the networknode 300. The wireless access information message may be used by the STA100 for determining whether or not to associate to the first wirelessaccess option, as will be described.

However, it should be noted that, in an embodiment, the STA 100 mayreceive the wireless access information message 306 without placing therequest 302 first. The wireless access information message 306 may bepresent in the beacon or other broadcasted frame that is transmittedwithout any request. Therefore, the transmission of the request message302 is optional.

The network node 300 may comprise at least one of an access point, suchas one of the APs 104 to 108, a base station, a Node B, an evolvedNodeB, and a server, such as the server 116 or a specific “discovery”server 124 capable of aiding the STA 100 in its association decision.Further, in an embodiment, each AP 104 to 108 may be configured toforward the request to the discovery server 124, if such exists. As oneexample, it may be mentioned that the STA 100 may send, e.g., a GenericAdvertisement Service (GAS) -request with a specific Access NetworkQuery Protocol (ANQP), or other protocol payload. The discovery server124 may be configured by the network operator, for instance, and the STA100 may not be aware of the specific server 124 that responses to therequest message 302.

In an embodiment, the discovery server 124 may be in the Internet 110,or it may be in one of the APs 104 to 108. Further, it should be notedthat different APs 104 to 108 may use different discovery servers.However, for the sake of simplicity, let us consider that the discoveryserver 124 is in the Internet as depicted in FIG. 1 with referencenumeral 124.

In an embodiment, the STA 100 may retransmit the request message 300 ifthe first response obtained does not comprise the information needed bythe STA 100. E.g. it may be that the response does not carry informationregarding the backbone link(s) 112/114 which is relevant to the firstand second wireless access options. For example, the STA 100 maytransmit the request message 302 first to the AP 104 and, if theinformation message 306 received as a response is not clear orsufficient, the STA 100 may issue a new request message 302 throughanother AP 106/108.

In an embodiment, the server, to which the request message 302 istransmitted to, is selected by the STA 100. It may even be that the APs104 to 108 are not aware of the existence or address of such server. Inan embodiment, the STA 100 may know the internet protocol (IP) addressof the discovery server 124 or the uniform resource locator (URL) oruniform resource identifier (URI) of the discovery server 124 andcontacts that specific discovery server 124. In one embodiment, thediscovery server 124 is hosted in the 3GPP LTE/LTE-A, or in some othercellular network.

The request message 302 may indicate the type of the request. In anembodiment, the request message 302 carries an indication of thecurrently associated at least one wireless access option, such as theassociated AP 104. In an embodiment, the request message 302 carries anindication of the capability to maintain concurrent associations, anindication of a number of maximum concurrent associations (depends onthe capabilities of the STA 100), and an indication of a preferrednumber of concurrent associations. The latter may depend on how muchdata needs to be transmitted to/from the STA 100, on the capabilities ofthe STA 100, for example. In an embodiment, the request message 302carries an indication on whether or not a cellular link of the STA 100is active. Further, the request message 302 may carry an indication onwhether or not the terminal 100 also supports concurrent use of thecellular radio, such as the LTE/LTE-A.

In an embodiment, the request message 302 further request the networknode 300 to indicate at least one other wireless access option to beassociated to concurrently with the already associated at least onewireless access option. Such wireless option may be the network withSSID=“4” via the AP 108, the network with SSID=“1” via the AP 106, thenetwork with the SSID=“2” or “3” via the AP 104, assuming the currentassociation is to the SSID=“1” via the AP 104.

In an embodiment, the request message 302 further requests the networknode 300 to indicate the capacity of the different wireless accessoptions in the location. The indicated capacity may comprise a nominalcapacity of the relevant backbone links 112/114, the APs' 104 to 108capability (capacity over the air), and/or the load of the APs 104 to108. In an embodiment, the capacity may be given in achievable data ratevia the least one concurrent association, for example. In an embodiment,the capacity may be given individually for each wireless access option.In an embodiment, the capacity may be given as aggregated capacity foreach possible combination of available wireless access option. This maybe beneficial as then the STA 10 may more sophistically perform adecision to which wireless access options the STA 100 should associate.

In an embodiment, the request message 302 further requests the networknode 300 to indicate or recommend a set of best candidate APs to beassociated with or maintained in a stand-by mode in the area of thecurrent location of the STA 100. The criteria for the “best” candidatesmay be predetermined by the discovery server 124, by the STA 100, and/orby the system.

In an embodiment, the request message 302 further carries an indicationof required communication resources. For example, the request messagemay include information related to applications that are installed inthe STA 100 and their data creation and/or reception characteristics. Inan embodiment, information of only those applications that are currentlyrunning or will be running in the STA 100 may be indicated in therequest message 302 302. Any application may provide its characteristicsto the controller of the STA 100 through socket options or by separatecontrol signaling. In addition to or alternatively, the STA 100 maymonitor data transfer characteristics of the STA 100 and, based on suchhistory knowledge, derive the characteristics of the data usage of theapplication(s). In addition to or alternatively, the use of configuredIP addresses and port numbers may enable acquisition of specificcharacteristics of the data usage of the application(s). In addition toor alternatively, an installation package framework of theapplication(s) may contain parameters from where the STA's 100 operatingsystem may derive some data usage characteristics for theapplication(s). It may be beneficial to indicate the possible datathroughput requirements as then the discovery server 124 may moresophistically propose a set of APs to associate with so that therequirements of the STA 100 may be fulfilled.

In an embodiment, the request message 302 further carries an indicationof the location of the STA 100, such as the cell ID of the cell wherethe STA 100 is at the moment, and/or information related to the movementof the STA 100, such as speed and direction of the movement of the STA100. This may provide information on available wireless access optionsfor the STA 100.

In an embodiment, the request message 302 further carries an indicationof the wireless access option which provides the strongest signalstrength, such as the strongest received signal strength indicator(RSSI), or an indication of the wireless option from which the STA 100expects to receive the best quality link.

In step 304, the network node 300 generates wireless access informationwhich may be used by the STA 100 in determining whether or not toassociate to the detected first wireless access option. In anembodiment, the determination may be based on knowledge of theconfiguration of the wireless access network configurations andtopologies. For example, the network node 300, such as one of the APs104 to 108 or the discovery server 124, may be aware how the routers120, 122, depicted in FIG. 1, connect to different backbones 112/114 andto different APs 104 to 108. Therefore, the information about howdifferent wireless access options interrelate with each other and howthey connect to the Internet 110 may be indicated to the STA 100 in thewireless access information message 306, i.e. in the response message306. The information provided by the network node 300 may enable the STA100 to select a more optimal set of the APs 104 to 108 to which theyestablish concurrent associations.

Alternatively or in addition to generation may be based on measurementperformed by the STA 100 or by some other STA, such as the STA 102. Inan embodiment, the information, on which the determination in step 304is based on, is updated on the basis of the measurement results from theSTA(s) 100, 102. More information on the application of the measurementinformation will be described later

Thereafter, in step 306, the network node 300, such as the discoveryserver 124, may transmit the wireless access information message 306 tothe STA 100. The wireless access information message 306 may carryparameters and information that are relevant for the STA 100 when itselects a set of APs 104 to 108 for association. The message 306 maycarry information on backbone network topology, such as whether or notthe first and the second wireless access options share at least part ofthe same backbone, for example. As a result, the STA 100 may, in step204, decide regarding the association to/with the first wireless accessoption.

It may be beneficial to request the response message 306 from thenetwork node 300 as the network node 300 may collect more information ofthe network performance than a single STA, for example. This informationmay help to detect possible bottlenecks of the performance (such as theshared backbone link 112). Further, when the response message 306carrying the relevant information is obtained, the STA 100 need notnecessarily use any resources for performing any radio measurements byitself.

In an embodiment, it is enough for the STA 100 to know whether or notthe backbone connection 112/114 of the available first wireless accessoption is likely to limit or increase the total throughput of the datacommunication or not. The information indicated in the wireless accessinformation message 306 may thus include a backbone IP address or anindication of which APs are connected to the same backbone (such as theAPs 104 and 106). For example, the knowledge that the first wirelessaccess option shares at least part of the backbone with the currentlyoperational (i.e. active) second wireless access option may indicatethat the first access option is not the optimal selection forassociation. In such case, the STA 100 may decide not to associate tothe first wireless access option as an active link, but to associate tothe wireless access option in a stand-by mode and/or to detect anotherwireless access option to associate to.

In an embodiment, the wireless access information message 306 furthercarries an indication of a set of at least one wireless access optionsfor the association by the STA 100. Further, the message 306 mayindicate a suggested association order for the indicated wireless accessoptions. Let us imagine that the wireless access options correspond tothe APs 104 to 108. The suggested order may provide guidance regardingthe suitability of the APs 104 to 108 in terms of communicationefficiency improvement. For example, if the STA 100 is currentlyconnected to the AP 104 and the message 306 indicates that the APs 104and 106 share at least part of the same backbone link 112 whereas theAPs 104 and 108 apply different backbones links 112 and 114, theindicated order may be such that the AP 108 is suggested before the AP106 as one possible AP to associate with. The use of such suggestionsmay reduce the complexity of the terminal implementation and providemeans for load balancing to the network. The suggestions may furtherhelp to maximize the performance of the STA 100 and avoid signalingoverhead, e.g. in cases where the STA 100 is moving and handovers may beperformed frequently.

When the first and second wireless access options use the same backbonelink 112, the message 306 may further indicate the priority of thewireless access options for resource usage. For example, in a congestionsituation, the high priority networks may be allocated a larger portionof the backbone capacity. Therefore, it may make sense for the STA 100to associate to a high priority wireless access option, rather than to alower priority wireless access option. The priority of the differentwireless access options may be preconfigured information and known bythe network node 300 generating the message 306.

Further, in an embodiment, when the backbone link 112/114 connectsmultiple radio access technologies (RATs), the message 306 may suggestone of the RATs for the device 100. For instance, in congestedsituations, one RAT may be closed completely in which case associationto such RAT may not be beneficial.

In an embodiment, the wireless access information message 306 furthercarries an indication of the communication performance available throughthe concurrent association with at least two wireless access options.Some embodiments may also provide information about the estimatedthroughputs for the uplink (UL) and for the downlink (DL) links. Theachievable/available throughput may be determined on the basis ofmathematical modeling. It should be noted that the discovery server 124may acquire knowledge about what the achievable data rates are for eachwireless access options, such as for each AP 104 to 108. A physical(PHY) transmission rate (in e.g. Mbit/s) may be set for each transmittedprotocol data unit (PDU). For example, the PHY transmission rate mayvary from 1 Mbit/s (802.11b) to approximately 1-2 Gbit/s (802.11ac).Further, the backbone routers and/or switches may report congestionsituation to the network node 300 (e.g. to the discovery server 124).This congestion information may be used when determining is the highestpossible data rate achievable through a given AP 104 to 108 or through agiven network SSID, for example. The congestion/utilization informationof the backbone network may thus help the discovery server 124 torecommend among the backbone links to the STAs 100, 102.

The response message 306 may further characterize the reason forassociating with a certain wireless access option. The reason may statethat association with the certain AP may increase the total throughputof the device 100 or that the association with the certain AP mayincrease the reliability of the communication, for example. The lattermay be the case when the total throughput is not increased by addinganother association. In such case, the association may still providemore reliability to the communication: if the current associationbecomes congested or otherwise fails, the new association may beactivated from the stand-by mode. Thus, the message 306 may also helpthe terminal 100 to select should the wireless access option be active(i.e. operational) or maintained only in the stand-by mode.

In an embodiment, the message 306 may also provide how the informationcarried in the message 306 was obtained (e.g. through measurements orthrough knowledge of the network configurations) and/or the time whenthe information which was used as a basis for the message 306 has beenacquired. This may enable the STA 100 to determine how up-to-date theinformation carried in the message 306 is. In case, it is older than apredetermined time limit, the STA 100 may decide to ignore the receivedmessage 306. Alternatively, upon detecting that the information storedand used as a basis for generating the message 306 in step 304 isexpired, the discovery server 124 may request for an update of theinformation. This may comprise requesting of an update of at least somemeasurement results from another network element, such as from one ofthe STAs 100, 102. In addition to or alternatively, the update of theinformation may comprise requesting the core network, routers, switches,etc. to update their input which may include network configuration,congestion situations, etc.

In an embodiment, as shown in FIG. 4, the network node 300, such as oneof the APs 104 to 106, the server 116 or any specific “discovery”server, may in step 400 determine whether or not a first wireless accessoption and a second wireless access option share at least part of thesame backbone, such as the backbone link 112/114. The network node 300may perform the determination on the basis of at least one of thefollowing: configurations of the first and second wireless accessoptions, indicated results of radio measurements performed by at leastone device, such as the user terminals 100, 102.

In step 402, the network node 300 may cause a transmission of a messageto the user terminal 100 capable to associate with both of the first andthe second wireless access options, wherein the message carriesinformation on the determination result. As said, the terminal 100 maythen use the received information in determining whether association toonly one or both of the wireless access options is to be done. Further,the received information may be used in determining which mode (activeor stand-by) to use in the associations, as will be described later.

Let us then look at how the STA 100 may perform the radio (link)measurements. In an embodiment, the STA 100 may also provide at leastsome of the measurement results to the network node 300. In anembodiment, as shown in FIG. 5 with solid bidirectional arrows 502 and504, the STA 100 may perform radio measurements, wherein the radiomeasurements comprise transferring data from a predetermined server 500through at least one of the first and the second wireless accessoptions. For reasons of clarity, the AP 104 is not depicted in FIG. 5.At least partly on the basis of the performed radio measurements, theSTA 100 may determine whether or not the first and the second wirelessaccess options share at least part of the backbone. Thus, in thisoption, the STA 100 need not necessarily receive the wireless accessinformation message 306 for performing the association decision. Forexample, when the network node 300 generating the message 306 does nothave information for these specific wireless access options in question,the radio measurements performed by the STA 100 may provide theinformation on whether wireless access options share at least part ofthe backbone. In an embodiment, the STA 100 makes the radio measurementswhile being in a pre-association or in an associated state with thecorresponding wireless access option.

The radio measurements may comprise throughput and/or capacitymeasurements. The radio measurements may comprise the terminal 100requesting DL data from at least one known server 500 and/or transmit ULdata to the at least one known server 500 via a specific wireless accessoption. The known server 500 may locate in the Internet, “behind” thebackbone links 112/114.

In one embodiment, during the radio measurements the terminal 100measures e.g. the transmission rate (in e.g. Mbit/s) and frametransmission success rate and utilization of the air interface. Itshould be noted that the STA 100 may not offer enough traffic to makethe backbone network congested when the air interface is congested, thetransmission rate is poor, and/or the transmission is too costly (moneyor energy-wise). The poor air interface performance may be detected inthe UL and in the DL transmissions by monitoring the number ofsuccessful transmissions and the transmission rate. If the obtainedthroughput is close to the rate that is obtainable over the airinterface, the STA 100 may consider that the maximum backbone throughputwas not yet measured and the STA 100 may consequently repeat the radiomeasurement via that wireless access option. The obtainable/achievablephysical layer (air interface) data transmission rate may be set foreach transmitted PDU, as indicated earlier. E.g. if the PHY transmissionrate is for instance 6 Mbit/s, the terminal 100 cannot transmit higheramount of traffic to the backbone link 112/114. As a result, the STA 100may only know that the backbone link 112/114 is capable to transmittraffic at minimum with the rate of 6 Mbit/s. In an embodiment, however,the backbone is faster than possible to measure over the air. In thiscase it may be determined that the backbone is not forming thebottleneck.

In an embodiment, the radio measurements with respect to a singleassociation are performed first, as shown e.g. with the solidbidirectional arrow 502. If the STA 100 has multiple associations tomultiple wireless access options, the STA 100 may repeat the radiomeasurements of a single association to all of its associations, asshown with the solid bidirectional arrow 504. In an embodiment, the STA100 may perform the backbone measurements through each of the at leastone of the first and the second wireless access options concurrently. Inanother embodiment the STA 100 may perform the backbone measurementsthrough each of the at least one of the first and the second wirelessaccess options in turns. In order to detect whether the throughput maybe increased by adding another active association, the STA 100 mayactively split its traffic across the different paths to determine thecombination of wireless access options, such as the combination of theAPs 104 to 108, which provides the optimal throughput. This may allowfor determination of the total throughput through the multipleconcurrent associations.

In an embodiment, if the STA 100 detected that the total throughput ofthe STA 100 decreases when the STA 100 has created a concurrentassociation to another wireless access option, such as to the AP 106,and started to transmit or receive data with both APs 104 and 106, theSTA 100 may consider that the APs 104 and 106 use the same, dependentbackbone link 112. In this case the concurrent association with both ofthe APs 104 and 106 may not improve the throughput of the STA 100. Insuch case the association to one of the APs 104 or 106 may be dropped ormaintained in a stand-by mode. The total throughput measured by the STA100 represents the accumulated throughput achieved through all theoperational associations. In addition, the radio measurements may reveala prioritization scheme of the wireless access options, such as of thenetworks with SSIDs “1”, “2”, “,3”, and “4”. That is, the networkprioritization may provide different throughputs with different networkassociations, for example, when the systems are loaded.

In an embodiment, the STA 100 implements software for actively and, inpurpose, testing the backbone performance and limitation through theradio measurements, as described above. The STA 100 may be a testequipment dedicated to perform such backbone tests, or the STA 100 mayuse some applications that cause the STA 100 to perform such backbonetests. In an embodiment, the user of the STA 100 may instruct the STA100 to perform measurements via certain wireless access options.

In an embodiment, the backbone throughput measurements may be performedor aided with other “assisting” devices, such as the STA 102. Themeasuring device 100 and the assisting device(s) 102 may togetherproduce more traffic to measure high throughput backbone links, forexample. Therefore, in an embodiment, the STA 100 performs the radiomeasurements during at least one other device, such as the 102, causesdata transfer 506 via the wireless access option which is under theradio measurements by the STA 100. The other STA 102 may be commanded toperform the data transfer, e.g. by the STA 100 or by another networknode 300, such as one of the APs 104 to 108 or the discovery server 124,for example.

In an embodiment, as shown in FIG. 6, the STA 100 may decide in step 600to request at least one other device, such as the STA 102, to performradio measurements in which the at least one other STA 102 transfersdata 506 from the predetermined server 500 through at least one of thefirst and the second wireless access networks. The data transmission bythe other STA 102 may take place concurrently with the data transmissionof the first STA 100. The reason for requesting other STA 102 to performthe measurements may be that the STA 100 does not yet have enoughinformation regarding the wireless access options available.

The assisting STA 102 may be commanded to perform the radio measurementby the discovery server 124, by one of the APs 104 to 108, or by the STA100 that is associated to the same AP, such as to the AP 108. Forexample, in an embodiment, the STA 100 may, in step 602A, transmit arequest frame to the AP 108 that is broadcasted to all STAs 102 in theBSS corresponding to the AP 108. The request frame may indicate the IPaddress of the server 500 which is to be used for the radio measurement,the direction (UL/DL) of the radio measurement, and indication of thewireless access option which is to be measured, such as the BSS(s) ofthe AP(s). In another embodiment, the STA 100 may directly contact theSTA 102, as shown with reference numeral 602B, if such radio connectionis possible between the two devices 100, 102.

In an embodiment, the request frame may request other STAs 102, that arewilling and capable to perform the radio measurements, to transmit anindividually addressed response frame to the transmitter 102 of thebroadcasted request frame. As shown with dotted line 604B, in anembodiment, the STA 102 may directly respond to the STA 100. If this isnot possible or successful, then in one embodiment, the STA 102 maytransmit the response frame to the AP 108 as shown with referencenumeral 604A. The AP 108 may then broadcast/forward the response frameto the STA 100. The response frame may provide the STA 100 with at leastone of the following of the responding STA 102: a medium access control(MAC) address, an IP address, maximum data transmission rate, radiocommunication capabilities.

Thereafter, on the basis of the response frame(s), the requesting STA100 may select in step 606 at least one of the devices 102 whichaccepted the request frame to assist in the radio measurements. Theselection may be based on the characteristics of the STA 102, such asthe maximum data transmission rate or the radio communicationcapabilities.

Thereafter, the requesting STA 102 may transmit a measurement startframe to the assisting device(s) 102 in step 608. Such backbonemeasurement start frame may contain an indication of the wireless accessoption that the assisting STA 102 is to measure, such as the BSS of theAPs 106 and 108, the measurement start time and/or the measurementduration, for example. Thereafter, the assisting device 102 may performthe data transfers to/from the predetermined server 500 via the AP 108,for example.

In an embodiment, the STA 100 may inform the at least one device 102causing the data transfer about certain restrictions for causing thedata transfer. For example, the restrictions may indicate that the atleast one device 102 is to start the data transfer after a predetermineddelay. In this embodiment, the STA 100 may request the assisting device102 to start its transmissions/DL reception later than the STA 100. Inthis operation, the STA 100 may measure how the obtained throughputchanges when the assisting device starts its own transmissions.

In an embodiment, the STA 100 may command the assisting device 102 totransmit/receive bursts of traffic. In this operation the STA 100 maydetect is its performance varying based on the bursty traffic.Similarly, in an embodiment, the STA 100 may command the assistingdevice to increase/decrease gradually its throughput and the STA 100 maytry to detect when its throughput is affected by the transmissions ofthe assisting device. If the performance/throughput changes due to theassisting device operation, the STA 100 may assume that the backbone isat least partially using the same bottleneck.

In an embodiment, the assisting device 102 may further transmit abackbone measurement information message 610 to the STA 100, wherein thebackbone measurement information message 610 carries at least someresults of the radio measurement performed by the STA 102. The STA 100receiving the backbone measurement information message 610 may thendetermine whether or not the first and the second wireless accessoptions share at least part of the backbone at least partly on the basisof the received measurement information message.

In an embodiment, the STA 100 and/or the STA 102 may also report themeasurement results to the network node 300, such as to the discoveryserver 124, so as to allow the discovery server 124 to update itsdatabase regarding different wireless access options, for example. TheSTA(s) 100, 102 may report the obtained throughput from the differentassociations when applying single associations and/or when applyingmultiple concurrent associations. The report may also comprise theassociation setup times to different wireless access options. Thenetwork node 300 may use the updated information e.g. later forassisting other devices which are requesting backbone performanceinformation from the network node 300.

In an embodiment, the STA may be offering the services of an AP. SuchSTA may, furthermore, by its own, periodically make performancemeasurements of its UL access.

It should be noted that possible multiple concurrent associations may bemaintained differently than only a single association. When the STA 100has multiple concurrent associations to maintain connectivity to theInternet 110, at least one link may be maintained in an active (i.e.operational) mode while other associations may be maintained in stand-bymode or in the active mode. The selected connectivity mode in theassociation may depend on the terminal's 100 traffic load, networkcongestion and/or the end-to-end traffic delivery (Internet backbone)performance and sharing.

In an embodiment, as shown in FIG. 7, the STA 100 may then decide instep 204 to associate to the first wireless access option, such as tothe network with the SSID “4” via the AP 108. Thereafter, in step 700,the STA 100 may further decide to associate the first wireless accessoption in the standby mode. As said, the STA 100 may acquire informationon whether two wireless access options share the same (bottleneck)transport/backbone link, such as the link 112. If yes, then addinganother path with the same bottleneck link 112 may not be beneficialfrom the point of view of the throughput at least. In some cases addinganother active association may even decrease the throughput asexperienced by the STA 100. In such case, the path may be added in thestandby mode to increase the reliability of the communication whileapplying another wireless access option for data transfer. Further, ifthe traffic load of the STA 100 is not high, then maintaining twoassociations in the active mode may not be needed.

In an embodiment, however, as the STA 100 detects that data transferperformance of a currently active wireless access option degrades, theSTA 100 may decide to change the stand-by mode of the first wirelessaccess option into the active mode in order to perform data transfer viathe first wireless access option. This may be beneficial from the pointof view of the data transfer efficiency. For example, when the currentlyactive wireless access option shows congestion or poor air interface, itmay be better to switch to start transferring data via the firstwireless access option that is currently in the stand-by mode. Thepreviously active wireless access option may be maintained in activemode, changed into the stand-by mode or dropped.

When the association is maintained in stand-by mode, the link is readyfor, e.g. authentication, association and IP addresses are created, butthe terminal has not directed traffic to the link. These preparationsspeed-up the transition and avoid delays to take the stand-by link intouse. However, in another embodiment, the STA 100 may in step 702 decideto operate with the first wireless access option in active modeconcurrently with the second wireless access option. This may be thecase when the acquired information indicates that the backbones 112 and114 are independent of each other, for example. Further, in cases wherea single well-performing association is not available, the STA 100 maymaintain more active associations. Examples of not well-performingassociations may comprise associations where the transmissions are notsuccessful or the air interface reliability is poor. In this case theterminal 100 may maintain multiple links and get retransmissions of theDL traffic or to select the UL link that offers the best performance.Multiple associations in this case enable the use of the both links andthe variation of the link performance may be measured and detectedimmediately. This operation may reduce the delay to make handovers andmultiple transmissions increase the probability of the successfultransmissions. A further example of not well-performing association maycomprise an association where the backbone throughput is not acceptableto meet the customer or application expectations. This may be detectedwhen the over-the-air transmission rates are high and the datatransmission over-the-air takes a small percentage of the totalavailable time. In this case, the wireless access options that areconcurrently associated should not share the same backbone, because thetotal capacity may be increased through independent backbone links.

The proposed solution for selecting the wireless access options, such asAP(s) 104 to 108, for concurrent associations and for deciding on theassociation maintenance/operation modes when the terminal is capable tooperate with concurrent associations may advantageously make the use ofthe concurrent associations faster and avoid unnecessary/unsuccessfulassociations.

FIGS. 8 and 9 provide apparatuses 800 and 900 comprising a controlcircuitry (CTRL) 802 and 902, such as at least one processor, and atleast one memory 804 and 904 including a computer program code (PROG),wherein the at least one memory and the computer program code (PROG),are configured, with the at least one processor, to cause the respectiveapparatus to carry out one or more of the embodiments described.

The apparatuses 800 and 900 may further comprise communicationinterfaces (TRX) 806 and 906 comprising hardware and/or software forrealizing communication connectivity according to one or morecommunication protocols. The TRX may provide the apparatus withcommunication capabilities to access the wireless local area network, ora cellular network, for example.

The apparatuses 800 and 900 may also comprise user interfaces 808 and908 comprising, for example, at least one keypad, a micro-phone, a touchdisplay, a display, a speaker, etc. Each user interface may be used tocontrol the respective apparatus by the user.

In an embodiment, the apparatus 800 may comprise the terminal device ofa cellular communication system, e.g. a user equipment (UE), a userterminal (UT), a computer (PC), a laptop, a tabloid computer, a cellularphone, a mobile phone, a communicator, a smart phone, a palm computer,or any other communication apparatus. Alternatively, the apparatus 800is comprised in such a terminal device. Further, the apparatus 800 maybe or comprise a module (to be attached to the apparatus) providingconnectivity, such as a plug-in unit, an “USB dongle”, or any other kindof unit. The unit may be installed either inside the apparatus orattached to the apparatus with a connector or even wirelessly. In anembodiment, the apparatus 800 may be, comprise or be comprised in a userterminal, such as the STA 100.

The control circuitry 802 may comprise a wireless access detectioncircuitry 810 for detecting the existence of a wireless access option,such as detecting a wireless access network or a wireless access point.An association control circuitry 812 may be for determining whether ornot to associate to the wireless access option(s) and, if yes, whetherto use an active or the stand-by mode for the association(s). Ameasurement circuitry 814 is for performing the radio measurements, suchas throughput measurements, or requesting other STAs to assist in themeasurements, according to any of the embodiments

In an embodiment, the apparatus 900 may be or be comprised in a networknode 300, such as in one of the APs 104 to 108 or in a specific serverin the network. The control circuitry 902 may comprise a networkawareness circuitry 910 for detecting and acquiring knowledge of thetopology and configuration of the networks. For example, the applicationof specific backbone connections by different routers/switches may bedetected. The congestion situation in the networks may be monitored aswell. A measurement analysis circuitry 912 may be for analysing radiomeasurement results provided by different STAs. The results may be usedfor updating the information of the networks, for example.

As used in this application, the term ‘circuitry’ refers to all of thefollowing: (a) hardware-only circuit implementations, such asimplementations in only analog and/or digital circuitry, and (b)combinations of circuits and software (and/or firmware), such as (asapplicable): (i) a combination of processor(s) or (ii) portions ofprocessor(s)/software including digital signal processor(s), software,and memory(ies) that work together to cause an apparatus to performvarious functions, and (c) circuits, such as a microprocessor(s) or aportion of a microprocessor(s), that require software or firmware foroperation, even if the software or firmware is not physically present.This definition of ‘circuitry’ applies to all uses of this term in thisapplication. As a further example, as used in this application, the term‘circuitry’ would also cover an implementation of merely a processor (ormultiple processors) or a portion of a processor and its (or their)accompanying software and/or firmware. The term ‘circuitry’ would alsocover, for example and if applicable to the particular element, abaseband integrated circuit or applications processor integrated circuitfor a mobile phone or a similar integrated circuit in a server, acellular network device, or another network device.

The techniques and methods described herein may be implemented byvarious means. For example, these techniques may be implemented inhardware (one or more devices), firmware (one or more devices), software(one or more modules), or combinations thereof. For a hardwareimplementation, the apparatus(es) of embodiments may be implementedwithin one or more application-specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, micro-controllers,microprocessors, other electronic units designed to perform thefunctions described herein, or a combination thereof. For firmware orsoftware, the implementation can be carried out through modules of atleast one chip set (e.g. procedures, functions, and so on) that performthe functions described herein. The software codes may be stored in amemory unit and executed by processors. The memory unit may beimplemented within the processor or externally to the processor. In thelatter case, it can be communicatively coupled to the processor viavarious means, as is known in the art. Additionally, the components ofthe systems described herein may be rearranged and/or complemented byadditional components in order to facilitate the achievements of thevarious aspects, etc., described with regard thereto, and they are notlimited to the precise configurations set forth in the given figures, aswill be appreciated by one skilled in the art.

Embodiments as described may also be carried out in the form of acomputer process defined by a computer program. The computer program maybe in source code form, object code form, or in some intermediate form,and it may be stored in some sort of carrier, which may be any entity ordevice capable of carrying the program. For example, the computerprogram may be stored on a computer program distribution medium readableby a computer or a processor. The computer program medium may be, forexample but not limited to, a record medium, computer memory, read-onlymemory, electrical carrier signal, telecommunications signal, andsoftware distribution package, for example. Coding of software forcarrying out the embodiments as shown and described is well within thescope of a person of ordinary skill in the art.

Even though the invention has been described above with reference to anexample according to the accompanying drawings, it is clear that theinvention is not restricted thereto but can be modified in several wayswithin the scope of the appended claims. Therefore, all words andexpressions should be interpreted broadly and they are intended toillustrate, not to restrict, the embodiment. It will be obvious to aperson skilled in the art that, as technology advances, the inventiveconcept can be implemented in various ways. Further, it is clear to aperson skilled in the art that the described embodiments may, but arenot required to, be combined with other embodiments in various ways.

1. A method, comprising: detecting, by an apparatus, a first wirelessaccess option; determining whether or not the first wireless accessoption shares at least part of a backbone with a second wireless accessoption; and deciding whether or not to associate with the first wirelessaccess option at least partly on the basis of the determination.
 2. Themethod of claim 1, further comprising: detecting the second wirelessaccess option.
 3. The method of any of claims 1 to 2, wherein theapparatus is associated with the second wireless access option whiledetecting the first wireless access option.
 4. The method of any ofclaims 1 to 3, wherein the shared at least part of the backbonecomprises a bottleneck to the Internet.
 5. The method of any of claims 1to 4, further comprising: causing a reception of a wireless accessinformation message from a network node, the wireless access informationmessage carrying an indication on whether or not the first and thesecond wireless access options share at least part of the backbone; anddetermining whether or not the first and the second wireless accessoptions share at least part of the backbone at least partly on the basisof the wireless access information message.
 6. The method of claim 5,wherein the wireless access information message further carries anindication of at least one of the following: at least one wirelessaccess option for association, the communication performance availablethrough the association with the at least one wireless access option, asuggestion for the order of association(s) with the at least onewireless access option.
 7. The method of any of claims 5 to 6, furthercomprising: causing a transmission of a request message to the networknode, wherein the request message is for receiving the wireless accessinformation message from the network node.
 8. The method of claim 7,wherein the request message further carries at least one of thefollowing indications: currently associated at least one wireless accessoption, capability to maintain concurrent associations, preferred numberof concurrent associations, and a number of maximum concurrentassociations.
 9. The method of any of claims 5 to 8, wherein the networknode comprises at least one of an access point, a base station, a NobeB, an evolved node B, and a server.
 10. The method of any of claims 1 to9, further comprising: performing radio measurements for determiningwhether or not the first and the second wireless access options share atleast part of the same backbone, wherein the radio measurements comprisetransferring data from at least one predetermined server through atleast one of the first and the second wireless access options; anddetermining whether or not the first and the second wireless accessoptions share at least part of the backbone at least partly on the basisof the radio measurements.
 11. The method of claim 10, furthercomprising: performing the radio measurements through each of the atleast one of the first and the second wireless access optionsconcurrently.
 12. The method of any of claims 10 to 11, furthercomprising: performing the radio measurements during at least one otherdevice causes data transfer via the wireless access option which isunder the radio measurements.
 13. The method of claim 12, furthercomprising: informing the at least one other device about restrictionsfor causing the data transfer, wherein the restrictions indicate atleast one of the following: the at least one other device is to startthe data transfer after a predetermined delay, the at least one otherdevice is to cause data transfer in bursts, the at least one otherdevice is to gradually increase or decrease the amount of data beingtransferred.
 14. The method of any of claims 12 to 13, furthercomprising: requesting the at least one other device to perform radiomeasurements in which the at least one other device transfers data fromthe at least one predetermined server through at least one of the firstand the second wireless access networks.
 15. The method of claim 14,further comprising: causing a reception of a radio measurementinformation message carrying at least some results of the radiomeasurements performed by the at least one other device; and determiningwhether or not the first and the second wireless access options share atleast part of the backbone at least partly on the basis of the radiomeasurement information message.
 16. The method of any of claims 1 to15, further comprising: upon deciding to associate with the firstwireless access option, deciding to associate the first wireless accessoption in a standby mode while applying another wireless access optionfor data transfer.
 17. The method of claim 16, further comprising:detecting that data transfer performance of a currently active wirelessaccess option degrades; and changing the stand-by mode of the firstwireless access option into an active mode in order to perform datatransfer via the first wireless access option.
 18. The method of any ofclaims 1 to 15, further comprising: upon deciding to associate with thefirst wireless access option, deciding to operate with the firstwireless access option in an active mode concurrently with the secondwireless access option in order to increase throughput.
 19. The methodof any of claims 1 to 18, wherein the first and second wireless accessoptions correspond to a same wireless access network provided by twodifferent access points
 20. The method of any of claims 1 to 18, whereinthe first and second wireless access options correspond to differentwireless access networks provided by a same access point or by differentaccess points.
 21. The method of any of claims 19 to 20, wherein thewireless access network is a wireless local area network.
 22. A method,comprising: determining, by a network node, whether or not a firstwireless access option and a second wireless access option share atleast part of a backbone; and causing a transmission of a message to auser terminal capable to associate with both of the first and the secondwireless access options, wherein the message carries information on thedetermination result.
 23. The method of claim 22, further comprising:performing the determination on the basis of at least one of thefollowing: configuration of the first and second wireless accessoptions, indicated results of radio measurements performed by at leastone user terminal.
 24. An apparatus, comprising: at least one processorand at least one memory including a computer program code, wherein theat least one memory and the computer program code are configured, withthe at least one processor, to cause the apparatus at least to: detect afirst wireless access option; determine whether or not the firstwireless access option shares at least part of a backbone with a secondwireless access option; and decide whether or not to associate with thefirst wireless access option at least partly on the basis of thedetermination.
 25. The apparatus of claim 24, wherein the at least onememory and the computer program code are configured, with the at leastone processor, to cause the apparatus further to: detect the secondwireless access option.
 26. The apparatus of any of claims 24 to 25,wherein the apparatus is associated with the second wireless accessoption while detecting the first wireless access option.
 27. Theapparatus of any of claims 24 to 26, wherein the shared at least part ofthe backbone comprises a bottleneck to the Internet.
 28. The apparatusof any of claims 24 to 27, wherein the at least one memory and thecomputer program code are configured, with the at least one processor,to cause the apparatus further to: cause a reception of a wirelessaccess information message from a network node, the wireless accessinformation message carrying an indication on whether or not the firstand the second wireless access options share at least part of thebackbone; and determine whether or not the first and the second wirelessaccess options share at least part of the backbone at least partly onthe basis of the wireless access information message.
 29. The apparatusof claim 28, wherein the wireless access information message furthercarries an indication of at least one of the following: at least onewireless access option for association, the communication performanceavailable through the association with the at least one wireless accessoption, a suggestion for the order of association(s) with the at leastone wireless access option.
 30. The apparatus of claims 28 to 29,wherein the at least one memory and the computer program code areconfigured, with the at least one processor, to cause the apparatusfurther to: cause a transmission of a request message to the networknode, wherein the request message is for receiving the wireless accessinformation message from the network node.
 31. The apparatus of claim30, wherein the request message further carries at least one of thefollowing indications: currently associated at least one wireless accessoption, capability to maintain concurrent associations, preferred numberof concurrent associations, and a number of maximum concurrentassociations.
 32. The apparatus of any of claims 28 to 31, wherein thenetwork node comprises at least one of an access point, a base station,a Nobe B, an evolved node B, and a server.
 33. The apparatus of any ofclaims 24 to 32, wherein the at least one memory and the computerprogram code are configured, with the at least one processor, to causethe apparatus further to: perform radio measurements for determiningwhether or not the first and the second wireless access options share atleast part of the same backbone, wherein the radio measurements comprisetransferring data from at least one predetermined server through atleast one of the first and the second wireless access options; anddetermine whether or not the first and the second wireless accessoptions share at least part of the backbone at least partly on the basisof the radio measurements.
 34. The apparatus of claim 33, wherein the atleast one memory and the computer program code are configured, with theat least one processor, to cause the apparatus further to: perform theradio measurements through each of the at least one of the first and thesecond wireless access options concurrently.
 35. The apparatus of any ofclaims 33 to 34, wherein the at least one memory and the computerprogram code are configured, with the at least one processor, to causethe apparatus further to: perform the radio measurements during at leastone other device causes data transfer via the wireless access optionwhich is under the radio measurements.
 36. The apparatus of claim 35,wherein the at least one memory and the computer program code areconfigured, with the at least one processor, to cause the apparatusfurther to: inform the at least one other device about restrictions forcausing the data transfer, wherein the restrictions indicate at leastone of the following: the at least one other device is to start the datatransfer after a predetermined delay, the at least one other device isto cause data transfer in bursts, the at least one other device is togradually increase or decrease the amount of data being transferred. 37.The apparatus of any of claims 35 to 36, wherein the at least one memoryand the computer program code are configured, with the at least oneprocessor, to cause the apparatus further to: request the at least oneother device to perform radio measurements in which the at least oneother device transfers data from the at least one predetermined serverthrough at least one of the first and the second wireless accessnetworks.
 38. The apparatus of claim 37, wherein the at least one memoryand the computer program code are configured, with the at least oneprocessor, to cause the apparatus further to: cause a reception of aradio measurement information message carrying at least some results ofthe radio measurements performed by the at least one other device; anddetermine whether or not the first and the second wireless accessoptions share at least part of the backbone at least partly on the basisof the radio measurement information message.
 39. The apparatus of anyof claims 24 to 38, wherein the at least one memory and the computerprogram code are configured, with the at least one processor, to causethe apparatus further to: upon deciding to associate with the firstwireless access option, decide to associate the first wireless accessoption in a standby mode while applying another wireless access optionfor data transfer.
 40. The apparatus of claim 39, wherein the at leastone memory and the computer program code are configured, with the atleast one processor, to cause the apparatus further to: detect that datatransfer performance of a currently active wireless access optiondegrades; and change the stand-by mode of the first wireless accessoption into an active mode in order to perform data transfer via thefirst wireless access option.
 41. The apparatus of any of claims 24 to38, wherein the at least one memory and the computer program code areconfigured, with the at least one processor, to cause the apparatusfurther to: upon deciding to associate with the first wireless accessoption, decide to operate with the first wireless access option in anactive mode concurrently with the second wireless access option in orderto increase throughput.
 42. The apparatus of any of claims 24 to 41,wherein the first and second wireless access options correspond to asame wireless access network provided by two different access points 43.The apparatus of any of claims 24 to 41, wherein the first and secondwireless access options correspond to different wireless access networksprovided by a same access point or by different access points.
 44. Theapparatus of any of claims 42 to 43, wherein the wireless access networkis a wireless local area network.
 45. An apparatus, comprising: at leastone processor and at least one memory including a computer program code,wherein the at least one memory and the computer program code areconfigured, with the at least one processor, to cause the apparatus atleast to: determine whether or not a first wireless access option and asecond wireless access option share at least part of a backbone; andcause a transmission of a message to a user terminal capable toassociate with both of the first and the second wireless access options,wherein the message carries information on the determination result. 46.The apparatus of claim 45, wherein the at least one memory and thecomputer program code are configured, with the at least one processor,to cause the apparatus further to: perform the determination on thebasis of at least one of the following: configuration of the first andsecond wireless access options, indicated results of radio measurementsperformed by at least one user terminal.
 47. An apparatus, comprisingprocessing means configured to cause the apparatus to perform the methodaccording to any of claims 1 to
 23. 48. A computer program productembodied on a distribution medium readable by a computer and comprisingprogram instructions which, when loaded into an apparatus, execute themethod according to any of claims 1 to 23.